In a decision declaring the method used to calculate a so-called growth score for a Long Island teacher to be "indisputably arbitrary and capricious," a state judge cited the findings of an array of experts who decried the approach as flawed, unreliable and open to bias against some teachers.

Acting State Supreme Court Justice Roger D. McDonough declined to prescribe an alternative to the state's "value-added" growth model, and he did not rule on the use of growth scores, which are tied to student test results, in general.

However, the 15-page decision he issued on May 10 offers a crash course on the reasons many experts are troubled by the way the state has attempted to connect teacher evaluations to student test scores. The lawsuit was filed by Sheri Lederman, a fourth grade teacher in Great Neck who received an "ineffective" growth score for 2013-14.

"The court fully recognizes that it does not have the educational background, resources or time to propose a meaningful replacement for New York's growth model system or to propose sound fixes for any arguable flaws of said system," McDonough wrote. Instead, he relied on expert evidence presented by Lederman's attorney and husband, Bruce Lederman, to support a determination that her growth score for 2013-14 should be invalidated and discarded.

McDonough was sharply critical of the state's use of a "bell curve" because it pre-determines what percentage of teachers must be included in each of four growth categories (highly effective, effective, developing or ineffective) every year. Professor Aaron M. Pallas of Columbia University noted that the categories remain consistent from year to year, regardless of whether students' test performance dramatically rose or fell in comparison to the previous year.

McDonough's ruling is specific to Lederman's circumstances, and the direct impact is restricted to her growth score for the one year. Still, it represents a black mark on New York's principal and teacher evaluation system, officially known as Annual Professional Performance Review (APPR).

New York State United Teachers applauded the ruling in Lederman's case. The union has also filed legal challenges to the growth formula.

Great Neck School Board President Barbara Berkowitz told On Board that board members are delighted that the judge "recognized the absurdity of the 'ineffective' rating that Mrs. Lederman received in 2013-14."

"Great Neck has numerous measures in place to review and evaluate the performance of our students and their teachers, and the intrusion of the state with the original ridiculous measurement criteria of APPR has been proven to be ineffective, inaccurate and severely flawed," she said.

McDonough's decision comes as Education Commissioner MaryEllen Elia is leading a multi-track reform review effort that includes crafting a proposal for a new evaluation system in time for implementation in the 2019-20 school year. In the meantime, the state has placed a moratorium on use of student test results in calculating APPR scores through the 2018-19 school year.

Lawyers for the state had argued that the moratorium, the plan to replace the growth model, and appeal procedures implemented for 2014-15 rendered Lederman's claims moot.

The State Education Department declined to comment on the decision, citing a policy of not commenting on litigation matters.

McDonough acknowledged the Education Department's "significant intellectual efforts and labor behind the development of the growth model system," which makes up one component of APPR. But he said Lederman offered "overwhelming submissions of evidence from learned experts in various relevant fields" that cite flaws in the value-added model (VAM).

Among other things, McDonough wrote, the state failed to adequately explain the "wild, statistically significant swing" in Lederman's scores from 2012-13 to 2013-14.

Sheri Lederman's challenge focused specifically on the growth component of her evaluation in 2013-14, which was based on her students' performance on state math and English language arts tests. She received 1 of a potential 20 points, which was defined as "ineffective." Her score the previous year was 14 of 20 points, or "effective," and her score the following year restored her growth rating to "effective."

The judge also noted that New York's growth model can be particularly distorting for teachers who, like Lederman, have classes made up mainly of high-performing students. Their students have slimmer room to improve, and the bell curve requires that a certain percentage must be rated as ineffective, even if all their students do improve.

In theory, the point of a value-added growth model is to measure an educator's contribution to the learning of students. The model attempts to make adjustments to be fair to teachers who serve groups of students who vary widely in circumstances, such as wealth or poverty, previous academic performance, native language and disabilities.

One expert who submitted affidavits on Lederman's behalf, Linda Darling-Hammond of Stanford University, criticized a lack of "controls for variables" related to school, home and classroom within New York's formula. According to the court decision, Darling-Hammond also found that controls for poverty, disability and English language ability "are not measured in a particularly nuanced fashion."